Put the dried beans in a large bowl, cover with cold water and leave to soak overnight.
Drain the soaked beans, put in a large saucepan and cover with the stock. Stir in the vegetables, bay leaf and crushed chillies and bring to the boil. Reduce the heat and skim off any scum that has risen to the surface. Simmer, uncovered, for 1 hour.
Stir the pearl barley and porcini into the pan and quickly return to the boil. Skim off any scum, reduce the heat and simmer for a further 30 minutes, or until the beans and barley are very tender.
Add the parsley, then check the seasoning, adding salt and pepper to taste. Serve with a scattering of grated Parmesan and a light drizzle of extra virgin olive oil.